Which line type is typically the lightest in a drawing?

The lightest line type in a drawing is the projection line. These lines are used to indicate the direction and points of projection from one view to another in technical drawings, such as orthographic projections. They are typically drawn as thin, continuous lines, ensuring that they do not overwhelm the main elements of the drawing while still providing essential information about the relationship between different views.

Projection lines help define the dimensions and shape of an object without adding unnecessary weight to the design, which is crucial for clarity and understanding in technical communication. Their lightness allows the viewer to focus on more prominent features of the drawing, such as the outline and detail lines, while still conveying the necessary layout information.

In contrast, other line types, such as outline solid or heavy contour lines, are bolder and meant to delineate the boundary and prominent features of an object. Hatching lines, often used to indicate surfaces or materials, have a specific purpose that also requires them to be more pronounced than projection lines. All of these reasons establish projection lines as the lightest in terms of visual weight in technical drawings.